His support of Whitman could aid ambitions. BY SASHA ISSENBERG WASHINGTON - From a Lexington office complex, Mitt Romney's political action committee has ensured the former presidential candidate's omnipresence on cable news shows, Republican rally stages, and antistimulus T-shirts, the last available with a $50 contribution to his Free and Strong America PAC. But for the next year and a half, the center of Romney's political universe will shift west to Sacramento, where key parts of his operation have reassembled on behalf of Meg Whitman, a longtime friend and former business colleague who this month entered next year's Republican primary...